If I thought there was any mileage in Corbyn's "caretaker" proposal, in order to block a no-deal Brexit, it might actually be worth writing about it. But, as Rafael Behr points out, it ain't going to happen. So we're back in bored to tears territory: I just wish they would get on with it and let me know when it's over.

Meanwhile, circulating Twitter and other internet spots like a bad smell that won't go away, is a paper written by Martin Howe QC and others, bearing the title: "Avoiding the Trap - How to Move on from the Withdrawal Agreement".

What is particularly vexing about this is that it supports the canard that the political declaration setting out the framework for the future relationship between the European Union and the United Kingdom (for short: the Political Declaration, or PD), linked to but separate from the Withdrawal Agreement, has somehow become legally binding – in whole or in part.

This is particularly said to be the case in respect of Defence capabilities development, contradicting the almost universal understanding that political declarations are not legally binding. And it is this false representation that I intend to address in this piece.

Before going any further, however, I need to make a point about the principal author of the paper, Martin Howe. Because he is a QC, he is often assumed to have a special authority when writing about treaty law and related matters. But, although he styles himself as a barrister in the fields of intellectual property and EU law, this is not in itself a qualification on treaty law, which is a very specialist field.

Additionally, even if he was knowledgeable in the field, in a strictly legal sense, he could never pass muster as an expert. In a court scenario, the requirement – established in case law - is that an expert should provide independent assistance to the court by way of objective unbiased opinion in relation to matters within his expertise. "An expert witness", says the guide, "should never assume the role of advocate".

This, I believe, should also cover the wider field. You can be an advocate for a point of view, or you can be an expert. You can't be both: if you are not unbiased, you can't claim to be an expert. And Martin Howe most certainly isn't unbiased. He is closely allied to the ERG and part of the "ultra" tendency, determined to sabotage Mrs May's Withdrawal Agreement. His paper can be seen as part of that process.

Then, there is an additional hurdle. The making of treaties and political declarations is part law but to a very great extent a political process. Especially in the case of political declarations, interpretation is determined as much or more by the politics as the law. And, in that area, a lawyer is not necessarily any more qualified to pronounce than any other knowledgeable person.

It is rather tiresome, therefore, to find that Howe – amongst those who value his point of view – is treated as some sort of minor deity, the supreme arbiter of all things relating to EU treaties. But, as we will see, he is very far from that.

Returning to the issue then, the central point (or assertion) is whether the Political Declaration is legally binding. And while the answer is well-known (no), it is difficult to find an authoritative source which confirms the principle. It's actually easier to define what is legally binding: a treaty. If it isn't a treaty registered with the United Nations, then it is not legally binding. A political declaration is not a treaty, so it's not legally binding. QED.

However - and as I remarked earlier, there is always a "however" in grown-up stuff – the test of whether something is a treaty is whether it creates legal obligations. The form and title doesn't matter. It's what it does that turns a document into a treaty.

On that basis, it is possible to have a political declaration, or elements of it, which creates legal obligations. In that case, although it may be called a political declaration, it will be a treaty – whence it becomes binding. The title "joint declaration", for instance, may be equally used for a legally binding agreement or non-binding statement of political intent.

Howe's endeavours, therefore, should have been directed at asking whether the Political Declaration, despite its title, is actually a treaty. But here, another point intervenes. If it is a treaty, then it is most certainly mixed, in which case it requires ratification by the UK and the 27 remaining Member States. Thus, it could never come into force because there are no plans to ratify it.

Stepping back from this, we need to take a brief look at the nature of the obligations which turn a mere document into a treaty. The key here, it seems, is enforceability in the courts. For that, one needs precision. If the "obligations" are of a general nature or simply aspirations or statements of intent, they cannot be enforced and cannot be legally binding.

On its website, Veterans for Britain nevertheless cite several instances where they believe the PD is legally binding. One such states:

… the Parties agree to enable to the extent possible under the conditions of Union law: a) the United Kingdom's collaboration in relevant existing and future projects of the European Defence Agency (EDA) through an Administrative Arrangement…

Applying the "precision" test, it seems to me that we would need: chapter and verse on "to the extent possible under the conditions of Union law"; a clear, unequivocal definition of what made a project "relevant"; and very specific details of what constituted an "Administrative Arrangement".

Without these points being established, the passage is too vague to be enforceable and cannot possibly be legally binding. Furthermore, the differences between the general principles and the detail can be many months of hard negotiation.

Needless to say, there are no absolutes. This website puts it in context. Whether an instrument imposes legal obligations, it says, "is a delicate issue of legal interpretation".

It goes on to say: "An imprecise or unclear formulation of the commitment in question often raises doubts as to its legally binding character, and an ambiguous or indeterminate clause may be construed only to reflect the parties' common understanding on joint political goals".

Predictably, this sails over the heads of Veterans for Britain, who have invented their own test. The provisions, they say, "are made functionally binding by the presence of the backstop in the WA (Withdrawal Agreement), which is legally-binding and that's all the EU needs". But that proposition, unknown in law, is absurd.

And yet Howe, in his paper, goes even further. "It is widely believed", he says, "that because the Political Declaration (PD) is 'not legally binding', therefore it does not really matter what it says. But this belief is utterly wrong". Actually, I don't believe that. In some circumstances, a political commitment can trump a legal obligation – it all depends.

In Howe's view, the PD "matters" because it is binding, by virtue of its links to the WA – which is a binding treaty (tautology). They are brought together by Article 184 of the WA. This, says Howe, "imposes an obligation on both the UK as well as the EU to use 'best endeavours in good faith' to negotiate an agreement which conforms to the PD".

Perceptive readers, however, might notice a slight problem with that assertion. This is what the PD actually says:

The Union and the United Kingdom shall use their best endeavours, in good faith and in full respect of their respective legal orders, to take the necessary steps to negotiate expeditiously the agreements governing their future relationship referred to in the political declaration … and to conduct the relevant procedures for the ratification or conclusion of those agreements…

As I recall it, this was inserted largely at the behest of the UK as a reassurance that the EU would not sit on its hands and take its time about agreeing the future relationship. There is no requirement that the final agreement should necessarily conform (in whole or part) with the PD.
But Howe has other ideas.

"The PD is vague in many areas, but where it is prescriptive, the EU will be legally entitled to insist on the UK seeking an agreement which complies with it. If the UK asks for something different, the EU will be fully entitled to say that the UK has not met the 'best endeavours in good faith' requirement in Art.184 and, thus, will be able to withhold agreement of the terms that we propose for the future UK-EU relationship".

Earlier, we had discussed the need for precision. Howe, on the other hand, has invented something entirely new to treaty law: "prescription". Where the PD is prescriptive, "the EU will be legally entitled to insist on the UK seeking an agreement which complies with it". Once again, though, this is a proposition unknown in law, in the context in which Howe seeks to place it.

Howe's turnkey is "good faith", but it is not as if there is not plenty of background to this in its legal context. In this website, linked to the other I cited, we see the concept explored in very great detail. It concludes:

Bona fides is a broad and value oriented concept. Due to its abstractness, it may inevitably contain the risk of an all too ambitious judicial activism. However, the predictability of a case's outcome might not be that much at risk if the decision-making body keeps in mind that bona fides is about legitimate expectations of the parties. Moreover, the mutual duties and obligations of international actors … cannot be determined in a purely formalistic way.

The take-home phrase, here, is "legitimate expectations" of [both] parties. Nothing here – nor in the entire exposition – can be taken as allowing this principle to turn a political declaration into a legally binding instrument. If you really want to get stuck in, read the entire tract.

The trouble is that Howe (undoubtedly deliberately) wants to make an obligation to negotiate the PD into an obligation to agree the text without departing in any way from it. That can't be done. The House of Commons Library researchers understand as much, even if Howe doesn't. They say:

The Political Declaration (PD) is not a binding legal document and it is unlikely that it will bind the parties to anything beyond a commitment to negotiate for a future relationship in good faith, which is set out in Article 184 of the Withdrawal Agreement.

Never mind, though. Howe has spoken on Brexit Central, the Telegraph and others have regurgitated his mewling. Another scripture has been added to the Brexiteer mantra, to be repeated ad nauseam. And that, in this country, is what passes for informed debate.